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Home , Seabed, Seamount

summary points

• Seamount classification system • Four key steps were identified in a process to identify and select potential Marine Protected Areas on (at the scale of an entire seamount as a minimum unit). • Define sets of physical characteristics to identify a range of types • Determine the level of replication required in each category from (1) • Determine the reserve size (30–50% of management area) • The general principle involved here is the use of physical information as a proxy for grouping seamounts in a biologically meaningful way. For most oceanic areas, there are few biological data, but knowledge of physical characteristics is more available, and able to guide seamount classification as a first cut until more information is collected. Seamount definition

• Seamounts are defined as geologic features (generally of volcanic origin) extending from the seafloor with an elevation of more than 1000 meters above the abyssal . The principles presented here can and should be applied to features that are geomorphologically distinct from, but ecologically similar to, seamounts. Such features may include: • 1) knolls, vertical elevation of 500-1000m, • 2) Banks • 3) slopes, • 4) , • 5) continental slope-associated features (e.g. intraplate volcanoes and hills) Seamount habitat type

• Substrate type • type will affect what fauna can occur (although acknowledged that most seamounts will have a wide range of substrate types) • Predominantly hard substrate (, rocky) • Predominantly soft substrate (mud, ) • Seamount shape • This will in part determine the amount and depth of substrate (especially on summit) • (-topped) • Conical small summit area • Connectivity • Distance between seamounts, and the relationship of seamount direction to current flow will affect the dispersal abilities of fauna • Isolated seamount • Seamount part of a cluster • Seamount part of a linear chain (includes ridge peak system) • Summit depth • Depth is a major determinant of species composition. As the seamounts by definition arise from abyssal depths (in most cases), elevation is also a relative measure of seamount size. • 0–200 m • 201–1000 m • 1001–2000 m • >2000 m • Oxygen concentration (OMZ) • Oxygen levels can also be important for survival of certain groups of species • 0–1 ml/l • 1–3 ml/l • >3 ml/l • Biogeographic zone • This reflects oceanographic conditions (water mass). Various zonation systems could be applied (e.g.. Longhurst, Large , Mexico Workshop) • Subtropical • Tropical • Subantarctic • Antarctic • Convergence/Frontal zone • Volcanic activity • This identifies whether communities may exist, and also whether volcanic activity such as flows could impose significant natural change. • Yes • No • Critical Ecological Habitat • Identifies the known presence of significant ecologically activity, such as the presence of VME, reefs, gardens, spawning grounds, nursery areas. This is seen as a SECOND TIER criterion, where biological knowledge will be applied to the initial selection of seamount groups based on the above physical parameters. • HOW THE SYSTEM CAN WORK • Use the above factors to create a number of groups of seamounts (e.g. hard substrate, summit depth <200 m, conical shape; hard substrate, summit depth 1001–2000m, guyot). • Identify seamounts within the groups for which biological information is available that may indicate critical ecological habitat. • Select 40% of the seamounts in each group (assuming entire seamount protected, based on number rather than size)

Then incorporate biological information where available and appropriate (below is Seamounts Online, April 2006, blue 0-10 records, green 10-20, yellow 20-30, orange 30-40, red >40) only red are likely to be of much use…).